1. Field of the Invention
This invention relates to a retraction-assisting device for retracting or for assisting the retraction of a drawer, which comprises two side walls and is in guiding contact with respective drawer-guiding corpus rails and carries respective coupling elements. Said retraction-assisting device comprises two guide housings, which are adapted to be fixed to respective ones of said corpus rails and each of which has forward and rear ends and contains a tension spring, which is fixed to said guide housing at said rear end thereof. A connecting member is pivoted to said tension spring at its forward end and comprises on one side a coupling portion, which laterally protrudes from said guide housing and has outside said guide housing an indentation adapted to receive one of said coupling elements. Said connecting member is slidably mounted in said guide housing, which comprises a trough that is defined by first and second guide flanges, which constitute linear guides for said connecting member. The connecting member is adapted to assume in said guide housing a drawer-coupling first angular position, in which said connecting member with said coupling element engaged in said indentation is movable toward said forward end of said guide housing to stress said tension spring. Said connecting member is arranged to assume under the stress of said spring adjacent to said forward end of said guide housing a drawer-releasing second angular position, in which said coupling element is disengageable from said coupling portion and adapted to re-engage said coupling portion in said indentation and to urge said coupling portion to said first angular position, whereafter said stressed tension spring is adapted to urge said connecting member with said coupling element engaging said coupling portion in said indentation toward said rear end of said guide housing.
2. Description of the Prior Art
Such a retracting or retraction-assisting device is basically known from WO 92/04843 A. That device is used to ensure that the drawer when it has been pushed in to a certain position will then automatically be urged to its fully retracted position and will be held in said retracted position by the springs, which have been tensioned during the extraction of the drawer.
In that known retraction-assisting device the linear guides merge into a widened portion adjacent to the forward end of the guide housing and said widened portion constitutes a slotted-cam guide for cooperating with the connecting member, which consists of a sliding member, to which the tension spring is laterally connected at its center. The coupling element has a rounded forward end, which is adapted to engage said guide housing in said slotted-cam guide, which first extends outwardly in an oblique direction and then merges into a straight portion, which is parallel to the linear guide, and is terminated by a stop wall. The connecting element has a beveled rear end portion, and for engagement with said rear end portion the linear guide has an outwardly directed arcuate portion, which is succeeded by a linear guiding portion. Between the arcuate portion and the linear guiding portion the slotted-cam guide comprises a corner-shaped portion, which constitutes a detent stop for said beveled end portion of the connecting member. As the drawer is extracted, the connecting member is tilted to assume an inclined position between the two linear portions of the slotted-cam guide whereas the beveled rear surface of the connecting member engages said arcuate portion.
The known design has the disadvantage that the guide housing is expensive because it must be wide enough to accommodate the slotted-cam guide so that the installation is difficult and the overall function is not exactly defined. There may be no proper interlock at the end of the extracting movement and in that case the connecting member may be pulled back to its initial position by the spring when the connecting member has released the drawer so that the retraction-assisting device will then be ineffective. Alternatively, the closing of the drawer may cause the coupling element to engage the connecting member and considerable pressure will then have to be exerted via the coupling element in order to effect a disengagement so that the connecting member will finally be disengaged with a loud noise. In view of the malfunction which is possible, the coupling portion comprises a catching device, and when the connecting member has not properly been coupled to the coupling element that catching device may be used to couple the connecting member once more to the coupling element when the drawer has been entirely retracted so that the drawer can subsequently be extracted.
EP-B 0 386 731 discloses a retraction-assisting device which comprises inside the guide housing a slotted-cam guide for guiding the connecting member. That slotted-cam guide comprises at its rear end a stop for engaging a guide pin of the connecting member and at the forward end has a curved portion, by which the connecting element is guided at the forward end of the guide housing to the second angular position, in which the coupling element is disengageable from the coupling portion. Whereas that design is reliable in operation, its overall expenditure is very high and its overall volume is rather large so that it is difficult to accommodate the device at the corpus rails. Another disadvantage of that retraction-assisting device resides in that the device cannot be mounted with the guide housing on the inside surface of the corpus rail so that the position of the coupling element relative to the indentation of the coupling portion may depend on the load on the drawer and there is a risk that the coupling member may not engage the coupling portion in the indentation as the drawer is inserted. It has been attempted to improve that design so as to decrease the overall volume and to provide an arrangement which permits the housing to be mounted on the underside of a corpus rail and to simplify the overall design by the provision of a trough-shaped housing, which is open toward the corpus rail. A EP-A 391 221 discloses a retraction-assisting device in which the connecting member is guided by means of two pins in a guide groove of the guide housing. In that case too the guide groove merges at its forward end into an arcuate guide for guiding the coupling portion to its angular position for extracting the drawer.
DE-A 41 24 512 represents an effort to provide a guide housing having a simpler linear guide. To that end, only a slider, which is connected to the spring, is mounted in the troughlike guide housing, and the indentation for locking the coupling element is formed in a segment which is pivoted to that slider. That segment comprises a feeler, which bears on a separate guide web, by which the segment is released at the forward end of the guide housing so that the coupling element can then leave the indentation. In that case too the composite assembly involves a high expenditure. The pivoting of the tiltable segment to the slider is not reliable in operation, and the overall volume is so large that the installation may be difficult.